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Car Forum / Jeep / October 2006Running Rich - 92-4.0L
I have a 92 Wrangler, 4.0L that is running real rich. Plugs go black, black smoke from exhaust. I put a new O2 sensor in a month ago, but it is still running rich. I have gone through and cleaned out the TB, and TPS & AIC sensors, still rich. What else could cause this? > I have a 92 Wrangler, 4.0L that is running real rich. Plugs go black, > black smoke from exhaust. [quoted text clipped - 4 lines] > > What else could cause this? Cheap ones first. - loose or broken vac line to the fuel pressure regulator? That results in too high a fuel pressure under normal operation. - Or too low a heat range on the plugs. If they are running cold they will soot up. Bad coil/weak spark that's not igniting each charge and letting some of the fuel through. leaking injectors (but usually that's only on one cyl). Clogged cat can result in backpressure problems. Any fault codes? http://autorepair.about.com/library/ts/obd-i/bl-dtcs-24a.htm  SignatureDougW Intake air temp sensor. Spdloader >I have a 92 Wrangler, 4.0L that is running real rich. Plugs go black, black > smoke from exhaust. [quoted text clipped - 3 lines] > > What else could cause this? A dirty air filter? Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > I have a 92 Wrangler, 4.0L that is running real rich. Plugs go black, black > smoke from exhaust. [quoted text clipped - 3 lines] > > What else could cause this? > A dirty air filter? Nope it's new > Cheap ones first. > - loose or broken vac line to the fuel pressure regulator? [quoted text clipped - 5 lines] > the fuel through. leaking injectors (but usually that's only on one cyl). > Clogged cat can result in backpressure problems. Previous Owner cut a hole in the cat and clean out the guts. It does leak a little, and I need to replace or bypass with a straight pipe > Any fault codes? > http://autorepair.about.com/library/ts/obd-i/bl-dtcs-24a.htm No Codes > Intake air temp sensor. > > Spdloader Can these be tested with a meter? >> Intake air temp sensor. > Can these be tested with a meter? Yes. they are just temperature sensitive resistors. (both mat and engine temp) http://revbeergoggles.com/Fixes/diagnostics.html SignatureDougW On 10/20/06 2:30 PM, in article Ts9_g.36203$iA5.20657@dukeread11, "DougW" <post.replies@invalid.address> wrote: >>> Intake air temp sensor. > [quoted text clipped - 3 lines] > resistors. (both mat and engine temp) > http://revbeergoggles.com/Fixes/diagnostics.html Cool, but its time to talk dummy language... How does that table convert to an Ohms reading? My gauge (old needle type) read from 0 to 1K. Great Web Site! > Cool, but its time to talk dummy language... > > How does that table convert to an Ohms reading? My gauge (old needle > type) read from 0 to 1K. The table is in ohms, 0-1k is 0-1000. There is probably a scale setting on your meter. Look for 10k or 100k. Worst off you can get a cheap digital meter at RadioShack, AutoZone, PepBoys, etc. > Great Web Site! I know I just stepped in on this one and it may have been suggested already, but I had a leaking exhaust manifold gasket. The air coming in (yes it did that) makes the O2 sensor think the engine is running lean and tells the computer to richen (is that a real word?) the mixture. After replacing the gasket and cleaning the sensor, my jeep ran better and mileage came back up. Simple fix. Well simple parts, but PITA to do. If you are having a whistling sound at highway speeds when feathering the gas pedal, that is a sure sign of it, that being said if it goes on long enough the whistling will go away. Got the t-shirt. Rich Harris >> Cool, but its time to talk dummy language... >> [quoted text clipped - 7 lines] > >> Great Web Site! "Enrich." Earle > I know I just stepped in on this one and it may have been suggested already, > but I had a leaking exhaust manifold gasket. The air coming in (yes it did [quoted text clipped - 18 lines] > > > >> Great Web Site! SignaturePosted via a free Usenet account from http://www.teranews.com Thanks Earl > "Enrich." > [quoted text clipped - 30 lines] >> > >> >> Great Web Site! > On 10/20/06 2:30 PM, in article Ts9_g.36203$iA5.20657@dukeread11, "DougW" > <post.replies@invalid.address> wrote: [quoted text clipped - 13 lines] > > Great Web Site! You 'really' don't want the VOM anywhere near the computer sensors. The load the meter puts on can fry computer circuits. Same for a test light. It's time to step up to a digital multimeter.... Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) >> On 10/20/06 2:30 PM, in article Ts9_g.36203$iA5.20657@dukeread11, "DougW" >> <post.replies@invalid.address> wrote: [quoted text clipped - 27 lines] > Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 > (More Off Road album links at bottom of the view page) Like a Fluke or it's equal. Spdloader >> A dirty air filter? >> [quoted text clipped - 25 lines] > > Can these be tested with a meter? When the sensor goes bad, it reports a cold condition that causes the system to go "full rich". Doesn't log a code, the computer just stays in cold start loop. Very common on GM 4.3 engines too. I don't have the operational parameters for testing with a meter, but someone here will. Spdloader > When the sensor goes bad, it reports a cold condition that causes the system > to go "full rich". Doesn't log a code, the computer just stays in cold start > loop. Very common on GM 4.3 engines too. > I don't have the operational parameters for testing with a meter, but > someone here will. I agree; the engine's probably stuck in open-loop mode. Older designs like this often have 2 engine temp sensors: 1 for the guage, 1 for the computer; if the computer temp sensor stops working for whatever reason, this will keep it open, as will bad O2 sensors. A really bad IAT will too. Older computers wouldn't set the MIL either. I have to wonder, if the cats were tampered with, if the owner also just pulled/disconnected the O2 sensors as well, which would cause this. |
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